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Steam Engine.

No. 236,875." Patented Jan. 25, 188i.

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UNITED STATES PATENT OFFICE.

ISAAC F. DAVIS, OF GREENSBOROUGH, NORTH CAROLINA.

STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 236,875, dated January 25, 1881.

Application filed May 6, 1880. (No model.)

To all whom it may concern Be it known that I, ISAAC F. DAVIS, of Greensborough, in the county of Guilford and State of North Carolina, have invented certain new and useful Improvements in Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the annexed drawings, making a part of this specification, and to the letters and figures'of referen ce marked thereon.

Figure 1 of the drawings is a representation of a side elevation of my steam-engine partly broken away to show my improvements. Fig. 2 is a plan view of the same, and Fig. 3 is a longitudinal sectional view.

The nature of my invention relates to double-cylinder steam-engines; and the improvement consists in dividing a single cylinder in two parts and providing each part with a piston, whereby either'one or both may be brought into action; also, in the combination, with a cylinder divided in two parts, of a double steam-chest; also, in the construction and arrangement of parts, as herein fully set forth, and particularly pointed out in the claims.

In the drawings, A designates the cylinder, which is divided into two parts, B B, by the centrally -located partition 0. Each part is furnished with a piston, D, the respective piston-rods of which pass through the ends of the main cylinder A. The piston-rod b of the part or cylinder B connects with the cross-head E, to which a pitman, F, is connected, as usual. The piston-rod b of the part or cylinder B connects with a cross-bar, G, which is secured upon the ends of connecting-rods H H, one of which works through a guide above the cylinder A, while theremaining connecting-rod works through suitable guides below the said cylinder. These connecting-rods also connect 5 with shorter connecting-rods I I, which are, in

turn, connected with the cross-head.

K designates the steam chest, arranged alongside of the cylinder A. This is formed into a double steam-chest by dividing it into two compartments by a partition, L. Each compartment (or, as it may be practically denominated, -chest) is provided with ports M, opening into the cylinders B B, as herein shown, so that thepistons willbe actuated by the steam independently of each other.

N N designate the valves, and O O the valve-rods. The valve-rod O of the chest or compartment opposite the cylinder B connects with a crossbar, P, to which is secured the connecting-rod Q. This rod connects with a shorter connecting-rod, R, and works through a suitable guide. The rod R connects by an arm with the connecting-rod Q which runs back to the usual connections with the eccentric S upon the crank-shaft T.

U designates the steam-pipe above the double chest, and V designates the arms of said pipe, which lead to the respective steam-chests.

W are the valve-cocks for letting on or cutting off steam from the chests.

The engine thus constructed may be used either to increase the rate of speed or to increase or lessen the horse-power, as follows: To double the speed, the connecting-rods of the cylinder B will be disconnected from the cross-head, and the steam shut oft from the chest which communicates with said cylinder. This throws all the steam into the cylinder B, which is one-half of the main cylinder A, thus doubling the rate of speed. To gain power the rods will be reconnected and the steam admitted into both compartments or chests of the double chest, whereby both pistons will be acted upon and actuated simultaneously in the same direction.

In thus forming one double cylinder and one double steam-chest, instead of having two separate cylinders andsteam-chests, as heretofore in double steam-engines, the heat will be held better and the steam will not condense nearly as much. The parts are all nearer together and more convenient, and the engine can be used as a portable, as well as a stationary, engine. There will be less friction, since but one crank and cross-head are employed.

More speed can be attained by having a short stroke, and at the same time more pressure be obtained in a small cylinder by having two plungers or follow-heads.

The partition in the cylinderAalso strengthens it.

Numerous other advantages might be enumerated; but these will be readily apparent to those skilled in the art.

I am aware that a double-cylinder engine is not broadly new, as such has been used both in England and America prior to my invention; butin all the cases coming under my observation no provision has been made in such engines for cutting off the steam from one of the cylinders and directing it into the other cylinder for the purpose of increasin g the speed of the engine, and by the same mechanism permitting the re-establishment of the steam-cow nection with both of the cylinders to increase the power.

What I claim is- 1. In a steam-engine, the combination of the double cylinders B B, having pistons D I), cross-head E, cross-bar G, connecting-rods H H and I I, double steam-chest K, and pipes U and V V, with valve-cocks \V W, constructed and operating substantially as and for the purposes set forth.

ISAAC F. DAVIS.

Witnesses A. P. EGKEL, J. W. MANGUM. 

